From 490f041717421ff7903c953775efe480a1ac3c1a Mon Sep 17 00:00:00 2001
From: wmayer <wmayer@users.sourceforge.net>
Date: Tue, 18 Mar 2014 11:27:52 +0100
Subject: [PATCH] + fixes #0001477: Spaceball becomes uncontrollable for large
 FreeCAD Documnets on X11 (spacenav)

---
 src/Gui/GuiApplicationNativeEventAware.cpp | 104 ++++++++++++++++++---
 1 file changed, 93 insertions(+), 11 deletions(-)

diff --git a/src/Gui/GuiApplicationNativeEventAware.cpp b/src/Gui/GuiApplicationNativeEventAware.cpp
index 171fb02cd..1e97f0abd 100644
--- a/src/Gui/GuiApplicationNativeEventAware.cpp
+++ b/src/Gui/GuiApplicationNativeEventAware.cpp
@@ -311,16 +311,83 @@ void Gui::GUIApplicationNativeEventAware::importSettings()
 bool Gui::GUIApplicationNativeEventAware::x11EventFilter(XEvent *event)
 {
 #ifdef SPNAV_FOUND
-    spnav_event navEvent;
-    if (!spnav_x11_event(event, &navEvent))
-        return false;
+    /*
+    First we check if we have a motion flush event:
+    - If there are unprocessed motion events we are in a flooding situation.
+      In that case we wait with generating a Spaceball event.
+    - A motion event counter of 0 indicates that FreeCAD is ready to process
+      the event. A Spaceball event, using the saved motion data, is posted.
+    */
+    static Display* display = QX11Info::display();
+    static Atom motion_flush_event = XInternAtom(display, "FCMotionFlushEvent", false);
+    static int nMotionEvents = 0;
 
     QWidget *currentWidget = this->focusWidget();
     if (!currentWidget)
         currentWidget = mainWindow;
 
+    if (event->type == ClientMessage)
+    {
+        Atom message_type = event->xclient.message_type;
+        
+        if (message_type == motion_flush_event)
+        {
+            nMotionEvents--;
+            if (nMotionEvents == 0)
+            {
+                importSettings();
+                
+                Spaceball::MotionEvent *motionEvent = new Spaceball::MotionEvent();
+                
+                motionEvent->setTranslations(motionDataArray[0], motionDataArray[1], motionDataArray[2]);
+                motionEvent->setRotations(motionDataArray[3], motionDataArray[4], motionDataArray[5]);
+
+                this->postEvent(currentWidget, motionEvent);
+            }
+            
+            return true;
+        } // XEvent: motion_flush_event
+    } // XEvent: ClientMessage
+
+    /*
+    From here on we deal with spacenav events only:
+    - motion: The event data is saved and a self addressed flush event
+              is sent through the window system (XEvent). 
+              In the case of an event flooding, the motion data is added up.
+    - button: A Spaceball event is posted (QInputEvent).
+    */
+    spnav_event navEvent;
+    if (!spnav_x11_event(event, &navEvent))
+        return false;
+
     if (navEvent.type == SPNAV_EVENT_MOTION)
     {
+        /*
+        If the motion data of the preceding event has not been processed
+        through posting an Spaceball event (flooding situation), 
+        the motion data provided by the incoming event is added to the saved data. 
+        */
+    	int dx, dy, dz, drx, dry, drz;
+
+        if (nMotionEvents == 0)
+        {
+            dx = 0;
+            dy = 0;
+            dz = 0;
+            drx = 0;
+            dry = 0;
+            drz = 0;
+        }
+        else
+        {
+            dx = motionDataArray[0];
+            dy = motionDataArray[1];
+            dz = motionDataArray[2];
+            drx = motionDataArray[3];
+            dry = motionDataArray[4];
+            drz = motionDataArray[5];
+        }
+        
         motionDataArray[0] = navEvent.motion.x;
         motionDataArray[1] = navEvent.motion.y;
         motionDataArray[2] = navEvent.motion.z;
@@ -329,14 +396,29 @@ bool Gui::GUIApplicationNativeEventAware::x11EventFilter(XEvent *event)
         motionDataArray[5] = navEvent.motion.rz;
 
         if (!setOSIndependentMotionData()) return false;
-        importSettings();
-
-        Spaceball::MotionEvent *motionEvent = new Spaceball::MotionEvent();
-
-        motionEvent->setTranslations(motionDataArray[0], motionDataArray[1], motionDataArray[2]);
-        motionEvent->setRotations(motionDataArray[3], motionDataArray[4], motionDataArray[5]);
-
-        this->postEvent(currentWidget, motionEvent);
+        
+        motionDataArray[0] += dx;
+        motionDataArray[1] += dy;
+        motionDataArray[2] += dz;
+        motionDataArray[3] += drx;
+        motionDataArray[4] += dry;
+        motionDataArray[5] += drz;
+        
+        /*
+        Send a self addressed flush event through the window system. This will
+        trigger a Spaceball event if FreeCAD is ready to do so.
+        */
+        nMotionEvents++;
+        XClientMessageEvent flushEvent;
+        
+        flushEvent.display = display;
+        flushEvent.window = event->xclient.window;
+        flushEvent.type = ClientMessage;
+        flushEvent.format = 8;    
+        flushEvent.message_type = motion_flush_event;
+        
+        XSendEvent (display, flushEvent.window, False, 0, (XEvent*)&flushEvent); // siehe spnavd, False, 0
+        
         return true;
     }